lex causae

[Latin: The law of the case]

This is the system of law that is applied to determine substantive issues of law in litigation, i.e. the law of the legal system that determines dispute. Where both of the litigants are local to the jurisdiction, and there is no foreign element involved, the lex causae will be English law (and the same as the lex fori). In international disputes, the lex causae may be different to that of English law, and depends upon the resolution in accordance with rules of conflicts of laws. 

Accordingly, where an international dispute relating to a contract governed by the laws of the United Stated is heard in the courts of England, the lex causae will be the laws of a state of the United States (that is, the law used to determine the substantive issues in dispute between the parties) and the lex fori will be the (procedural) laws of England. 

Also referred to as the lex loci causae.

Usage: The court determined that the laws of New York was the lex causae in the litigation.

Related Words: lex fori; proper law of the contract; jurisdiction clause; conflict of laws; lex situs; litigation; abuse of process; lex domicilii; jurisdiction; anti suit injunction; lex contractus; foreign judgment; lex solutionis; choice of law clause; contract; lex posterior derogate priori; recognition of foreign judgments; locus standi; lex scripta; lex non scripta.